title: Thermo-optical bistability with Si nanocrystals in a whispering gallery mode resonator.
abstract: We report on the observation of optical bistability in an integrated planar microresonator with embedded silicon nanocrystals (Si-ncs). The phenomenon originates from the thermo-optical modulation of the silica-embedded Si-ncs refractive index, which in turn alters the spectral position of the resonator mode. The estimated thermo-optical coefficient of the Si nanocrystalline material, dn/dT≈2.92×10(-5)>  K(-1), is an order of magnitude lower than that of bulk silicon. Both time-resolved pump-and-probe experiments and numerical simulations confirm that the silica host is responsible for the heat dissipation from the resonator. Moreover, a negligible Q-factor degradation at pump powers as high as 100 mW, along with the absence of a fast component in time-resolved measurements, confirm the minute contribution from excited carriers effects. These observations, combined with the already published large third-order nonlinearities of Si-ncs (an order of magnitude larger than in bulk Si), make this system an outstanding candidate for low-power on-chip nonlinear comb generation.
authors.forename: F
authors.initials: F
authors.lastname: Ramiro-Manzano
authors.forename: N
authors.initials: N
authors.lastname: Prtljaga
authors.forename: L
authors.initials: L
authors.lastname: Pavesi
authors.forename: G
authors.initials: G
authors.lastname: Pucker
authors.forename: M
authors.initials: M
authors.lastname: Ghulinyan